Adjuvant Aromatase Inhibitor Therapy for Breast Cancer
Name of the Trial
Why This Trial Is Important
Anastrozole (Arimidex) and exemestane (Aromasin) are two AIs approved by the FDA to treat early-stage, hormone receptor-positive breast cancer. Anastrozole is a reversible inhibitor that competes with estrogen precursor molecules for binding to aromatase; exemestane attaches permanently to aromatase, preventing estrogen precursors from binding to the enzyme at all (making it an irreversible "suicide" inhibitor). Exemestane also exerts androgenic (male hormone-like) effects in women, and this may contribute to its anticancer efficacy while possibly causing fewer side effects.
In this clinical trial, postmenopausal women with hormone receptor-positive breast cancer that has been surgically removed will be randomly assigned to receive either anastrozole or exemestane for 5 years. Doctors will monitor breast cancer recurrence and the side effects of these drugs. Separate companion studies will examine whether there is a difference in how the drugs affect bone mineral density and breast density in these patients; only those locations enrolling patients in the breast density companion study (NCCTG-N0434) are currently accepting patients for the AI study.
"While anastrozole and exemestane have not been compared previously in a clinical trial, evidence from preclinical studies and other clinical trials comparing each agent to tamoxifen support the idea that exemestane may be a more potent inhibitor of aromatase and have androgenic effects that may be important in enhancing efficacy and affording a better side effect profile," Dr. Goss said.
For More Information
An archive of "Featured Clinical Trial" columns is available at http://www.cancer.gov/clinicaltrials/ft-all-featured-trials.